1. Field of the Invention
The present invention relates to an apparatus for filtering metallic shavings from liquid lubricant in an axle, and more particularly to lubricant circulating through the wheel hubs mounted on at the axle ends.
2. Description of the Problem
Rear drive axles for motor vehicles provide lubrication for moving parts within the axle, including the power distribution gears (the differential) and the bearings located in the axle ends for the wheel hubs. Lubricating oil circulates outwardly from the differential housing through the axle to the wheel hubs and returns by the same channel in the axle to the differential housing during cornering. During vehicle operation metal shavings may form off the differential gears and become suspended in the lubricating oil due to the continuing agitation of the differential ring gear. These metallic shavings can circulate to and through the wheel hubs, causing damage to or wear of the roller bearings located there through abrasion. The shavings may foul the bearings reducing the flow of lubricant, accelerating these negative effects.
Filtration of metallic shavings in the differential housing to protect the differential is known in the art. For example, U.S. Pat. No. 3,847,249 to Oehring teaches providing a lubricant filtration system located in the differential housing. The filtration system was simple to construct, easy to service and reliable in operation, requiring only infrequent service. During vehicle operation oil is splashed against the interior of the differential housing by action of the differential gears. Oehring provides a filter comprising a lubricant receptacle positioned between the periphery of the large differential ring gear and the top of the differential housing to collect oil dripping from the interior housing surface. The filter unit provides a relatively large area for lubricant flow, a large area for filtered lubricant distribution, and a particle collection cavity in which separated solid particles can accumulate without adversely affecting the filtration function by filter media blockage. In one form, mechanical filtration was supplemented by magnetic separation of metallic particles from the lubricant. Such a filtration system provides no guarantee of thorough filtering of the oil, and the rate of exchange between oil in the wheel hubs and the differential housing may be very slow, with the consequence that oil reaching the wheel hubs may not be filtered. This can allow metal bearing oil to reach the hubs with the consequential risk of damage to the wheel bearings.
According to the invention there is provided a magnetic filter for installation in a wheel hub. The magnetic filter fits within the wheel hubs, which are mounted for rotation on each end of the axle. The wheel hub rotates on a plurality wheel hub bearings disposed on the end of the axle in contact with the wheel hub. The axle includes a channel allowing lubricating oil to reach the wheel hub bearings. The lubricating oil filter is positioned in the lubricating oil path between the wheel hub bearings and the channel, so that all oil reaching the bearings passes through the hub, and is mounted with the wheel hub for rotation. The lubricating oil filter comprises a circular ring section which fits into an annular plenum in the wheel hub and includes flow directing barriers positioned radially inwardly from an outer edge of the circular ring section. Centripetal acceleration will promote separation of the more massive metal shavings from the lubricating oil. Constructing the ring of a magnetic material promotes retention of the metal shavings on the ring. Construction of the ring from a spring material, and the provision of gaps or holes through the filter, allow fitting the ring into the plenum without fasteners.
Additional effects, features and advantages will be apparent in the written description that follows.